Page 251 - Understanding Automotive Electronics
P. 251
2735 | CH 7 Page 238 Tuesday, March 10, 1998 1:15 PM
7 DIGITAL ENGINE CONTROL SYSTEM
Figure 7.7a
Idle Air Control
FPO
When the engine is not idling, the idle speed control valve may be
completely closed so that the throttle plate has total control of intake air.
During periods of deceleration leaning, the idle speed valve may be opened to
provide extra air to increase the air/fuel ratio in order to reduce HC emissions.
Figure 7.7b
Idle Air Control
238 UNDERSTANDING AUTOMOTIVE ELECTRONICS
